Cooling systems for motor driven pumps and the like

ABSTRACT

Cooling systems for motor driven pumps and the like are disclosed which include the use of a sub cooler applied to motor driven pumps and the like that impel low boiling fluids and include provisions for bleeding a small portion of the pumped fluid, flashing the fluid for cooling, using the vapor to cool the pumped fluid and/or circulating the vapor around the pump to cool the bearing and other critical areas susceptible to excessive heating.

sited States Patent 1 COOLING SYSTEMS FOR MOTOR DRIVEN PUMPS AND THE LIKE [75] inventor: Reinald G. Magni, Croydon, Pa.

[73] Assignee: Crane C0., New York, NY.

{22] Filed: Oct. 7, 1971 [21] Appl. No.: 187,361

{51] Int. (11. F04b 39/02, F04b 39/06 [58] Field of Search 417/366, 368, 369, 417/370, 371, 901, 84; 62/505, 45, 55; 60/260 [56] References Cited UNITED STATES PATENTS 3,241,331 3/1966 Endress et a1. 62/505 X 2,292,617 8/1942 Dana 417/901 X 1 .Euiy 10, 1973 11/1929 Frickey et 417/366 2/1971 Hall 60/39.46 X

Primary Examiner-Carlton R. Croyle Assistant Examiner-R. J. Sher Attorney-George S. Schwind 5 7 ABSTRACT Cooling systems for motor driven pumps and the like are disclosed which include the use of a sub cooler applied to motor driven pumps and the like that impel low boiling fluids and include provisions for bleeding a small portion of the pumped fluid, flashing the Fluid for cooling, using the vapor to cool the pumped fluid and- /or circulating the vapor around the pump to cool the bearing and other critical areas susceptible to excessive heating.

6 Claims, 6 Drawing Figures E g //0 l/o/ Patented July 10, 1973 3 Sheets-Sheet l COQLENG SYSTEMS FOR MOTOR DRIVEN PUMFS AND THE LIKE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a cooling system for motor driven pumps and the like wherein a portion of the pumped fluid is flashed and circulated to cool the pumped fluid, and/or portions of the pump subject to excessive heating.

2. Description of the Prior Art it has heretofore been proposed to cool motor driven pumps for liquids and the like and which have a motor stator isolated from the motor rotor by an interposed sleeve by circulating a portion of the liquid being pumped in the interior of the sleeve and in contact with the motor rotor and also to utilize part or all of that portion of the liquid for lubricating and cooling the motor bearings. See, for example US. Pat. No. 3,280,750.

it has also been proposed to apply cooling coils to the exterior of the motor housing and circulating liquid therethrough for cooling. One example is shown in US. Pat. No. 3,127,530.

Low boiling point fluids such as fluorinated hydro carbons, chlorine, ethane, and liquid nitrogen that vaporize at low temperatures and at high pressures are extremely difficult to handle in pumps. Unless a high static column of a low boiling point fluid is maintained on the suction side of the pump, the pumped fluid may flash off to a vapor causing cavitation and loss of liquid film in the bearing journals which can result in severe damage to the pump.

Various structures have heretofore been proposed as a solution to this problem such as increasing the suction forces on the lubricating fluid or the volume used for cooling but none have proven wholly satisfactory. The present invention utilizes a sub cooler to cool the pumped fluid before it enters the pump and provides for cooling the critical areas of the pump so as to maintain the temperature at a level to avoid flashing of the fluid in the bearings and in other pump areas where such flashing would be undesirable.

SUMMARY OF THE INVENTION in accordance with the present invention cooling systems are provided for motor driven pumps and the like which pump low boiling point liquids, the systems having a sub cooler to reduce the temperature of part or all of the liquid being pumped and to provide cooling at selected locations or critical pump locations such as the motor hearings to prevent the lubricating fluid from flashing in the bearing journals with resulting loss of fluid lubricating film in the bearings.

The principal object of the invention is to provide cooling systems for motor driven pumps and the like which pump low boiling point fluids by using the expansion heat absorbing characteristics of the pumped fluid to cool the pumped fluid and locations susceptible to excessive heating.

A further object of the invention is to provide cooling systems for motor driven pumps and the like which circulate low boiling point fluids and which is easily applied to various types of pumps.

A further object of the invention is to provide a cooling system for pumps for low boiling point fluids that is inexpensive to construct but reliable in operation.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRlPTlON OF THE DRAWINGS The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part thereof, in which:

FIG. 1 is a fragmentary central sectional view of a portion of a typical motor driven pump with the appa ratus of the invention applied thereto;

FIG. 2 is a vertical sectional view taken approxi mately on the line 2-2 of FIG. ll;

FIG. 3 is a diagrammatic view of a cooling system in accordance with the invention;

FIG. 4 is a diagrammatic view of another cooling system in accordance with the invention;

FIG. 5 is a diagrammatic view of another cooling system in accordance with the invention; and

FIG. 6 is a diagrammatic view of still another cooling system in accordance with the invention.

it should, of course, be understood that the description and drawings herein are illustrative merely and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings and H68. 2 and 2 thereof, a typical motor driven pump such as is shown in US. Pat. No. 3,280,750 is illustrated and includes an impeller housing 10 with a fluid inlet or intake connection ii and an impeller chamber 12. The impeller chamber 12 is enclosed within a scroll 14 of well known type. The impeller housing 10 has a fluid delivery connection 15 formed thereon and communicating with the scroll 14. The housing 10 has an end face 26 with a liner plate 17 aligned therewith and which plate 117 is secured to a motor housing end plate 18. The plate 13 has an inner face 19 in meeting relation to the end face 16 of the housing 10.

The end plate i8 is part of a motor housing 20 which contains a motor stator 21 with windings 22 and stator laminations 23.

The liner plate 18 has a motor stator isolating sleeve 25 secured thereto in fluid tight relation. An inwardly extending boss 24 secured to the plate 18 extends within the sleeve 25.

A fluid impeller 30 is disposed within the scroll l4 and is carried on a hollow shaft 311 journaled in bearings 32 mounted in the boss 24.

A cooling tube 33 is provided outside of the sleeve 25 and inside of the motor housing 20 to cool the windings 22 and the bearings 32. The tube 33 has an intake orifice 34 and an outlet connection 35.

Referring now to FIG. 3 one embodiment of the invention is there shown which includes a source of low boiling point fluid, such as fluorinated hydrocarbon, chlorine, ethane, liquid nitrogen and the like to be pumped which source has a pipe lltlll connected thereto and to a sub cooler assembly MP2. The sub cooler assembly 102 is directly connected to the inlet side 103 of a motor driven pump MP4 of well known type and as previously described. The motor driven pump that has an outlet connection m5 with a pipe 106 connected thereto for delivery of the fluid being pumped.

The sub cooler 102 includes a cooling tube 107 which is spirally wound about the interior of the cooler 102 for cooling contact therewith of fluid supplied to the pump inlet 103. The cooler 102 is provided with an intake expansion orifice 108 and an outlet connection 109.

A pipe 110 is connected to pipe 101 to divert a small portion of the fluid in pipe 101 to the orifice 108. The outlet connection 109 has a pipe 111 connected to it and to a pipe 112 which is connected to a condensing compressor 113 of a type commonly used in refrigeration and cooling systems and then to a condensing coil 114. The coil 114 has a pipe 115 connected to it and to the fluid source 100.

The pipe 110 extends to an expansion orifice 120 within a cooling tube 121 which extends around the interior of a pump 104 as shown in FIGS. 1 and 2 and with an outlet connection 122 having a pipe 123 connected to it and to pipe 112.

In operation, a portion of the fluid being pumped in pipe 101 is diverted by pipe 110 to expansion orifice 108 where it flashes to vapor in tube 107 and absorbs heat from the fluid which passes through sub cooler 102 and is in contact with the tube 107. The vapor in tube 107 is exhausted through outlet 109, through pipe 111 to pipe 112 and to condensing compressor 113 and condensing coil 114 where it is returned to a liquid state and is then returned through pipe 115 to source 100.

A portion of the fluid in pipe 110 flows through orifice 120 where it flashes to vapor in the tube 121 absorbing heat from pump 104 and the vapor is exhausted through outlet 122 and to pipe 123 to pipe 112 and to condensing compressor 113 and condensing coil 114 to supply 100.

Referring now to FIG. 4 in the embodiment there shown a fluid supply source 200 has a pipe 201 connected thereto and through a sub cooler assembly 202. The sub cooler assembly 202 is connected to the fluid inlet side 203 of a motor driven pump 204 as previously described. The pump 204 has an outlet connection 205 with a fluid delivery pipe 206 connected thereto for delivery of pumped fluid as desired.

The sub cooler 202 has a cooling tube 207 therein spirally wound therearound with an intake expansion orifice 208 and an outlet connection 209. A pipe 210 is connected to a pipe 201 and to orifice 208 to divert a small amount of fluid to the expansion orifice 208.

The outlet connection 209 has a pipe 211 connected thereto and to an eductor 212 of well known type. The pipe 210 extends to an expansion orifice 220 at the inlet of a cooling tube 221 which extends around the interior of the housing of the motor driven pump 204 as shown in FIGS. 1 and 2. A vapor exhaust connection 222 is connected to the tube 221 and by the pipe 223 to the pipe 211. The pipe 206 has a small pipe 225 connecJed thereto and to the nozzle (not shown) of the eductor 212 for tapping off higher pressure fluid to mix with and carry the vapor from the pipe 211 into pipe 201 through pipe 226. The cooling operation proceeds as previously described with the high pressure fluid at the nozzle of the eductor 212 from pipe 225 evacuating the low pressure vapor delivered thereto by pipe 211 and carrying it back to pipe 201 through pipe 226.

Referring now to FIG. 5 another embodiment of the invention is illustrated which includes a fluid supply source 300 with a pipe 301 connected thereto and to a sub cooler assembly 302. The sub cooler assembly 302 is connected to the inlet side 303 of a motor driven pump 304. The motor driven pump 304 has an outlet connection 305 with a fluid delivery pipe 306 connected thereto for delivery of pumped fluid as desired. The sub cooler 302 has a cooling tube 307 therein spirally wound around the interior with an intake expansion orifice 308 and an outlet connection 309.

A pipe 310 is connected to pipe 301 and to orifice 308 to divert a small amount of fluid to the orifice 308. The outlet connection 309 has a pipe 311 connected thereto. The pipe 310 extends to an expansion orifice 320 at the inlet end of cooling tube 321. The cooling tube 321 extends around the interior of the housing of the pump 304 as previously described. A vapor exhaust connection 322 is connected to the tube 321 and by a pipe 323 to the pipe 311. A pipe 324 is connected to pipe 311 and to the intake 325 of a positive displacement condensing compressor 326 of well known type connected to and driven by the motor driven pump 304. A pipe 327 is connected to the outlet from compressor 326 and carries the liquid from the compressor back to the source 300.

The operation of this system is similar to that previously described for FIG. 3 except that the vapor is condensed by compressor 326 driven by the motor driven pump 304 and does not therefore require an outside coil system for vapor condensation.

Referring now to FIG. 6 another embodiment of the invention is shown in which a fluid supply source 400 has a pipe 401 connected thereto and directly to the inlet 402 of a motor driven pump 404, the motor driven pump 404 being the same as is shown in FIGS. 1 and 2. The motor driven pump 404 has an outlet connection 405 with a fluid delivery pipe 406 connected thereto for delivery of pumped fluid as desired.

The outlet 405 has a small pipe 407 connected thereto and to the intake side of a heat exchanger or evaporator 408 of well known type. The outlet 409 from the exchanger 408 has a pipe 410 connected thereto and to the pump 404 at the left to supply cooled fluid for use as a lubricant and for cooling the pump 404.

The pipe 401 has a pipe 412 connected thereto and to an expansion orifice 414 of the heat exchanger 408. The heat exchanger 408 has a cooling tube 415 therein spirally wound around in contact with the fluid from pipe 407. An exhaust outlet connection 416 is provided for tube 415 with pipe 417 connected thereto and to an eductor 420 of well known type.

The eductor 420 has a pipe 421 connected to its nozzle (not shown) from pipe 406 for tappling off higher pressure fluid to deliver fluid in the pipe 417 back to the source 400.

In operation a portion of the fluid from the pump outlet 405 in pipe 407 passes through the heat exchanger 408 where it is cooled as a result of the action of the fluid flashing in orifice 414 and absorbing heat as it flows through tube 415 and to the outlet 416. The cooled fluid from the heat exchanger 408 is carried through pipe 410 to the hollow shaft of the motor driven pump 404 where it cools the pump bearings and other areas susceptible to heating and is mixed with the fluid at the fluid inlet 11 as shown in FIGS. 1 and 2.

The vapor from heat exchanger 408 passes through outlet 416 and through pipe 417 to eductor Q and then through pipe 422 to the supply 4M).

The vapor pressure of the vaporized fluid can be held about It to l2 psig below the suction pressure of the motor driven pump and the temperature of the vapor will be of the order of 12 to 16 F. below the process fluid temperature. Since the heat of vaporization of these fluids is from 120 to 150 times the specific heat of the liquid a relatively small cooling system is capable of high heat rate removal.

lit will thus be seen that apparatus has been provided with which the objects of the invention are attained and which utilized the vaporization of a part of the fluid being pumped to effect cooling at desired locations.

i claim:

1. Cooling apparatus for motor driven pumps and the like for low boiling point liquids which comprises a source of low boiling point liquid to be pumped,

a motor driven pump having inlet and delivery connections and having the inlet connection connected to said source for the introduction of said liquid to the inlet connection and pump,

means for diverting a portion of the liquid from said source and vaporizing said diverted portion in predetermined cooling relation to said pump,

fluid delivery means returning the vaporized liquid in liquid form to said source, and

said diverting and vaporizing means includes heat exhangc means interposed between the source and the pump inlet connection for cooling the liquid delivered to the pump inlet connection.

2. Cooling apparatus as defined in claim 1 in which said fluid delivery means includes a compressor 3. Cooling apparatus as defined in claim 2 in which said compressor is connected in driven relation to the motor of said motor driven pump.

4. Cooling apparatus as defined in claim 2 in which said fluid delivery means also includes separate cooling means.

5. Cooling apparatus as defined in claim l in which said diverting and vaporizing means includes an expansion orifice, and

a heat exchanger into which fluid is expanded through said orifice.

6. Cooling apparatus for motor driven pumps and the like for low boiling point fluids which comprises a source of low boiling point fluid to be pumped,

a motor driven pump having inlet and delivery connections and having the inlet connection connected to said source,

means for diverting a portion of the fluid from said source and vaporizing said diverted portion in predetennined cooling relation to said pump,

fluid delivery means returning the vaporized fluid in liquid form to said source, and

a fluid connection is provided from the delivery connection of the pump to the inlet connection of the pump, and

said diverting and vaporizing means includes heat exchange means cooling the fluid in said fluid connection. 

1. Cooling apparatus for motor driven pumps and the like for low boiling point liquids which comprises a source of low boiling point liquid to be pumped, a motor driven pump having inlet and delivery connections and having the inlet connection connected to said source for the introduction of said liquid to the inlet connection and pump, means for diverting a portion of the liquid from said source and vaporizing said diverted portion in predetermined cooling relation to said pump, fluid delivery means returning the vaporized liquid in liquid form to said source, and said diverting and vaporizing means includes heat exchange means interposed between the source and the pump inlet connection for cooling the liquid delivered to the pump inlet connection.
 2. Cooling apparatus as defined in claim 1 in which said fluid delivery means includes a compressor.
 3. Cooling apparatus as defined in claim 2 in which said compressor is connected in driven relation to the motor of said motor driven pump.
 4. Cooling apparatus as defined in claim 2 in which said fluid delivery means also includes sEparate cooling means.
 5. Cooling apparatus as defined in claim 1 in which said diverting and vaporizing means includes an expansion orifice, and a heat exchanger into which fluid is expanded through said orifice.
 6. Cooling apparatus for motor driven pumps and the like for low boiling point fluids which comprises a source of low boiling point fluid to be pumped, a motor driven pump having inlet and delivery connections and having the inlet connection connected to said source, means for diverting a portion of the fluid from said source and vaporizing said diverted portion in predetermined cooling relation to said pump, fluid delivery means returning the vaporized fluid in liquid form to said source, and a fluid connection is provided from the delivery connection of the pump to the inlet connection of the pump, and said diverting and vaporizing means includes heat exchange means cooling the fluid in said fluid connection. 